Question

Why does the oscillation of a simple pendulum eventually stop?

Answer 1

the oscillation of a simple pendulum eventually stop becuae the force putten on it has been ended and time period is over.

Answer 2

The oscillates of a simple pendulum are damped oscillations.  Most of the oscillations in air or in any medium are damped. When an oscillation occurs, some kind of damping force may arise due to friction or air resistance offered by the medium. So, a part of the energy is dissipated in overcoming the resistive force. Consequently, the amplitude of oscillation decreases with time and finally becomes zero. Hence the oscillations of a simple pendulum eventually stops.